Bone distraction and the associated osteogenesis is a process by which bone growth is promoted by cutting a bone and separating it in a controlled manner. As the separation of the bone at the fracture site takes place, new bone is formed in the intervening space created by the separation. Originally, this technique was developed for lengthening the long bones in the body, but was later broadened and is now applied to many parts of the body including the bones in the craniofacial area.
In particular, promoting bone growth in the jaw (mandible) has been under investigation and development for several years to address known deformities associated with the lack of bone in that region. Various surgical procedures have been developed to address bone growth in the craniofacial area and likewise, various appliances have been devised for bone distraction in the craniofacial area.
One of the most common techniques presently in use is cutting the mandible at the apex of the arch and installing a rapid palatal expander (RPE) by affixing its legs to one or more teeth on opposite sides of the palatal arch. Alternatively, the legs of known RPE's can be attached directly to the mandibular bone, or a combination of teeth and bone. The patient (or clinician) then regularly activates the device with a key (pin) which is turned a desired amount daily to achieve the widening effect. One drawback to this technique of utilizing RPE's currently on the market is that the device operates strictly in a linear manner by spreading the cut mandibular bone linearly. This linear spreading may cause the condyles to move laterally out of their sockets, which is highly undesirable. Additionally, many RPE's currently available are bulky and cannot be easily accommodated in patients who have narrow jaws, which is the reason they are undergoing the distraction osteogenesis to begin with. Furthermore, RPE's typically have sharp edges and are not designed to come into direct contact with the soft tissues of the patient's oral cavity. Moreover, the overall rigidity of the RPE may be compromised when the bone is completely distracted. Lastly, the required daily activation of the device can be particularly difficult when the device is affixed in the posterior section of the mouth.
Therefore, what is needed is an expansion (or contraction) device for patients undergoing bone distraction or tooth movement having a smooth finish and a lack of sharp edges such that it can be placed in contact with the soft tissue while expansion (or contraction) is taking place. It is further desired to have a device for use in bone distraction or tooth movement where the movement created is simultaneously in more than one plane of space.